The present invention relates to a method and apparatus for reading DX bar codes and frame number bar codes printed on edges of photographic film and to a method of determining conditions for setting the photographic film on a film carrier based on the reading of such bar codes.
DX bar codes representative of a film type (maker and film sensitivity) are printed as a latent image on an edge portion of a negative film, e.g. of 135 type, the DX bar codes being made visible upon development. The DX bar code is constructed of a clock track used for reading timings, and a data track on which data are recorded, both tracks being printed on opposed major edges of the negative film. The DX bar code is read with a bar code sensor unit at the time of printing or at the time of inspecting the quality (color balance and density) of the frame image. The read-out data are used in calculating the exposure amount for printing.
It also is known that a bar code representation of a frame number is printed along an edge of a photographic film. The frame number bar code is used. e.g.. for searching for a desired frame to obtain additional prints thereof and automatically setting it at the print stage of a printer for recording a frame number on some area of the print to dispense with the comparison work between a print and the frame, and for other reasons.
Printing both DX bar codes and frame number bar codes along edges of a photographic film necessitates use of different types of bar codes to allow discrimination therebetween. Moreover, it becomes necessary to use two bar code sensor units, each dedicated to one of the two types of bar codes and mounted on a film carrier at both sides of a film passage. However, it is necessary to set the film on the film carrier in one of two predetermined directions, with either the smallest or the largest frame number at the start position. If a film is set in the wrong direction, neither of the bar codes can be read correctly. Also, if a film is set upside down in the film carrier the bar codes cannot be read correctly, and a photograph printed from the rear side is produced, resulting in loss of material and work time.
Even if a read error occurs for one of the DX bar codes, the following DX bar code which is edge-printed at equal intervals on the film may be read, thus posing no problem. However, only one frame number bar code is present for each particular frame, so that if the bar code sensor unit erroneously reads the frame number, the incorrectly read frame number when set at the print stage cannot be identified.